Flavoprotein which are involved in electron transfer are located in inner mitochondrial membrane and accepts the electrons from primary dehydrogenases and transfer to electron transferring flavoprotein dehydrogenase which finally transfer them to coenzyme Q in a normal mechanism.
So if flavoprotein transfers the electrons directly to final electron acceptor it would produce a highly potent oxygen radical "hydrogen peroxide". Apart from this the other effect would be;
The less protons would be pumped to intermembrane space of mitochondria and ultimately the production of ATP would be decreased.
The energy of electrons would be lost in heat as it is not utilized for the production of ATP so there would be more heat production.
Evolution includes the change in the heritage characteristics of the organism population as subsequent generations substitute each other. These were all communities of developing organisms but not single individuals. In evolutionary terms, the relative efficiency of an organism is assessed by its contribution to the next gen's gene pool.
Enzymes are protiens that control the speed of chemical reactions in your body therefore without these them the reactions would take place too slow for you to live.